Dante Viggiano, 20, was seen at the two-family home on Venus Place two or three weeks before the deadly botched burglary Sunday that killed Peter Gialluisi, 67, and left his wife, Vincensa Gialluisi, 66, in the hospital, according to police and witnesses.

“This crazy guy, he was here two or three weeks ago,” said Vincensa’s brother, Angelo Gallo, 74. “I see him from upstairs. He came around here, came up the driveway and he’s looking at the house.”

Gallo, who lives upstairs from his sister, confronted Viggiano as he lurked around the house and specifically asked for Peter.

“I say, ‘Can I help you?’ and he says, “I’m looking for Pete.’ I said `Pete’s not here’, though he was in the living room, I ask how do you know Pete? And he said from the phone book. But I know that the number is not listed,” said Gallo. “He got a crazy look in his eyes and turn back at the house and looked, a very strange look.”

Gallo said he instantly recognized the intruder after he heard his sister’s screams Sunday.

“I turn and see him running out the front door and I remember his face – I knew. It was the crazy guy from before,” Gallo said.

Gialluisi and his wife were returning from a birthday party for the couple. Gallo had been with his sister and her husband just moments before the attack. Gallo exited their vehicle and went upstairs before the couple was surprised by the intruder.

Viggiano was awaiting arraignment at Bellevue Hospital where he was undergoing a psychiatric evaluation. He had been at Staten Island University hospital for wounds he suffered during the attack, cops said.

His mother, Donna, was trying to make sense of it all.

“This has been a great shock to us,” she said.” My son was diagnosed with paranoid schizophrenia four years ago. He was never violent. We’re very, very shocked.

“We’re as shocked as the victim’s family. My heart goes out to (the victim’s) family. I am devastated for her (the stabbing survivor), and I’m devastated that my son would do such a horrible thing.”